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Hum Physiology II > Lect 6 > Flashcards

Lect 6 Flashcards

1
Q

Na+ regulation responds primarily to changes in what? What is the primary effector?

A
  • blood volume/blood pressure
  • primary effector: renin-angiotensin-aldosterone system
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2
Q

water regulation responds primarily to changes in what? What is the primary effector?

A
  • osmolarity and volume of ECF
  • primary effector: antidiuretic hormone
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3
Q

what is the function of aldosterone

A
  • stimulates sodium reabsorption in the late distal tubule and collecting duct (principle cells)
  • stimulates K+ secretion
  • only 2% of filtered Na+ is under control of aldosterone
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4
Q

increases in what stimulate aldosterone release

A
  • angiotensin II or plasma K+
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5
Q

what receptor does aldosterone bind to

A

intracellular mineralocorticoid receptor in principle cells

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6
Q

aldosterone-MR receptor complex stimulates transcription resulting in up-regulation of what four things

A
  • apical ENaCs
  • apical K+ channels
  • NA+-K+-ATPase
  • mitochondrial metabolism
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7
Q

aldosterone is antagonized by what diuretic

A

spironolactone

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8
Q

list the multiple effects of angiotensin II

A
  • vasoconstrictor
  • stimulates release of aldosterone
  • stimulates Na+/H+ (NHE) exchange in proximal tubule
  • stimulates thirst
  • **functions favor salt retention and elevation of arterial blood pressure
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9
Q

angiotensin II levels are controlled by what enzyme

A

renin

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10
Q

renin is released by JGA via what 3 mechanisms: describe the intrarenal baroreceptors

A
  • granular cells of JGA respond to pressure (stretch) in afferent arterioles
  • release of renin inversely related to pressure in afferent arterioles
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11
Q

renin is released by JGA via what 3 mechanisms: describe the role of macula densa

A
  • macula densa senses flow to distal tubule
  • renin release inversely related to GFR
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12
Q

renin is released by JGA via what 3 mechanisms: describe the role of renal sympathetic nerves

A
  • renal sympathetic nerves (RSN) end near granular eclls
  • stimulation of RSN increases renin release via stimulation of Beta receptors
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13
Q

List out the RAAS pathway

A

angiotensinogen - (1) -> angiotensin I - (2) -> angiotensin II

  1. renin
  2. ACE
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14
Q

where is atrial natriuretic peptide released from? What is it released in response to?

A
  • atria
  • when pressures are high
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15
Q

what effect does atrial natriuretic peptide have on afferent and efferent arterioles

A
  • ANP dilates the afferent arteriole and constricts the efferent arteriole
  • increases GFR
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16
Q

how does atrial natriuretic peptide decrease NaCl reabsorption by the collecting duct

A
  • directly inhibits secretion of renin and aldosterone
  • directly inhibits Na+ uptake by medullary Collecting duct
17
Q

what is the most important hormone regulating water balance

A

ADH

18
Q

where is antidiuretic hormone released from? it is released in response to?

A
  • pituitary
  • when plasma osmolarity increases of plasma volume decreases
  • *ADH has little effect on NaCl excretion
19
Q

where are receptors for ADH located?

A
  • basolateral membrane of collecting duct
    • activation results in cAMP production
20
Q

what two mechanisms sense changes in homeostasis and lead to release of ADH

A
  • hypothalamic osmoreceptors sensitive to small changes in plasma osmolarity (1%)
  • hypovolemia stimulates ADH secretion via arterial and left atrial baroreceptors
21
Q

ADH has what functions

A
  1. increase permeability of the CD to water (aquaporins)
  2. increase Na+/Ka+2Cl- (NKCC2) transporters in the LOH
  3. increase permeability of inner medullary CD to urea
22
Q

what is osmolar clearance and what is the equation?

A
  • ml/min of blood plasma cleared of osmotically active particles
  • Cosm = (Uosm)(V) / (Posm)
23
Q

what does a reduced osmolar clearance indicate

A
  • positive osmolar balance -> gaining osmoles -> progression to edema
  • decreased GFR, increased aldosterone, or any disease that decreases the ability of the kidney to eliminate solue
24
Q

what does a increased osmolar clearance indicate

A
  • “dumping” osmolytes, leads to a loss of ECF
  • diuretics, reduced aldosterone, or any disease that reduces the ability of the kidney to reabsorb normally

Hum Physiology II (12 decks)

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